Method and apparatus for heat exchange, where channels, e.g. tubes, are secured in recesses in heat-isolating boards

ABSTRACT

A method of heat exchange comprises advancing energy-carrying medium in a channel system comprising channel-part lengths (1) which extend in side-by-side mutually parallel relationship, such as hose parts (1), and substantially sheet-like or slab-like base parts (2) which support the channel parts. The method is mainly characterized by supporting and holding channel parts (1) with the aid of at least one pre-fabricated sheet or slab (2) of heat-insulating material, such as so-called cellular plastic material, and by inserting the channel parts (1) into locking grooves (3, 4) included in the slab or sheet, the width of locking grooves, when appropriate, being preferably slightly smaller than the width of a channel part, in appropriate cases the diameter of the channel part. The invention also relates to an arrangement for carrying out the method.

The present invention relates to a method of heat-exchange, comprisingadvancing an energy-carrying medium in a channel system comprisinglengths of mutually parallel channel parts, such as hose parts, andsupporting said channel parts with the aid of a substantially sheet-orslab-like base element.

The invention also relates to an arrangement for carrying out themethod.

The invention is intended primarily for application in the constructionof artificially frozen ice-rinks or like playing areas, but can also beapplied to produce all kinds of large heat-exchange surfaces, such asso-called heated floors, solar-energy collectors, etc.

In conventional methods of producing artificially frozen playing areas,steel pipes are cast in a concrete bed or anchored loosely in a gravelbed, and, refrigerant, such as ammoniacal liquid, is caused to expandand evaporate. The energy required herefor is taken from the ambientsurroundings of the pipes, therewith cooling the surroundings.

Later solutions utilize indirect evaporation techniques, i.e. afrost-protected liquid is chilled with the aid, for instance, of ammoniaor freon and is circulated in the channel system of the ice rink, pitchor like area concerned. The pipes used may be made of a plasticsmaterial. The plastic pipes are anchored in reinforcement netting or thelike and-are embedded or anchored in some other way, and then coveredwith gravel, such as to provide a cooling surface for the production ofan artificially frozen ice-rink or like area.

According to one method of laying cooling pipes in gravel beds, there isfirst formed a layer of asphalt concrete which is provided with grooveson the outer surface thereof for accommodation of the cooling pipes. Thecooling pipes, often in the form of hoses, are then placed in thegrooves and surrounded or packed with sand, up to the level of the upperedge of the asphalt layer. The surface is covered with a fibre fabric,for instance a geofabric, and a layer of gravel material is laid to adepth of about 50 mm, with the intention of preventing the hoses frommoving out of the grooves as a result of linear expansion in summertime. The hoses are thus held in position by the weight of the gravel incombination with pressure distribution from the fibre fabric. The hosesplaced in said asphalt grooves or in some other grooved material canalso be covered with concrete, which anchors the hoses and protects thesame against mechanical action and the effect of degrading UV-light. Aconstruction of hoses in a grooved base material covered, for instance,with gravel or concrete can be used as a cooling surface forartificially frozen ice rinks, as a heated floor or as a solar energycollector on the ground, on a separate framework or on the roof of abuilding.

An analysis has shown that the following technical desiderata andconsiderations are common to such constructions:

Heat transfer from/to the undersurface of the construction should bescreened with an insulating material, so as to direct heattransportation from/to the hoses to a layer which essentially covers theouter layer of the construction.

The hoses should be densely packed, so as to achieve a largehose-surface area and therewith a more uniform distribution oftemperature from/to said surface layer and lower resistance to heattransportation through the walls of the hoses.

It should be relatively simple to anchor the hoses in conjunction withplacing said hoses on the base element, since varying temperatures andsolar radiation will result in an increase/decrease of the hosetemperature, therewith causing the hoses to move prior to being finallyanchored, by packing said hoses with an appropriate material.

The material packed around and over the hoses, up to the surface of theconstruction, should have a high thermal conductivity, so as to achievethe lowest possible temperature drop through said material. The materialshould also be in good contact with the outer surfaces of the hoses, soas to achieve the lowest possible resistance to the transfer of heatto/from the hose walls.

The thermal mass of the covering material will influence the reactionrate in the construction when the thermal load from/to the surface ofthe construction varies. For instance, a decrease in the temperature ofthe refrigerant in the hoses of an artificially frozen ice rink, or anincrease in the temperature of a heat carrier in a heated floor isconsiderably delayed with changed temperatures on the surface of theconstruction in proportion to the thickness of the covering layer andthe total thermal mass.

The present invention relates, to a solution in which rational assemblyincorporating a small number of mutually different components isintegrated in a construction which includes screening insulation on theundersurface, thereof, dense hose distribution, locking of hoses againstlongitudinal and vertical movement, low heat-transfer resistance fromhoses to covering material and a low coefficient of thermal conductivityand low thermal mass of the covering material, said solution eliminatingthe drawbacks of known solutions and providing important advantages inthe form, inter alia, of effective use of energy and good drainage.

The invention thus relates to a method of heat exchange in which anenergy-carrying medium is advanced in a channel system comprisingmutually parallel and adjacent channel parts, such as hose parts, andsupporting said channel parts on essentially sheet or slab-like basemembers. The method is mainly characterized in that channel parts arecarried and held by at least one pre-fabricated sheet of heat-insulatingmaterial, such as so-called cellular plastic material, and in that saidchannel parts are laid-out in locking grooves formed in said sheet and,when applicable, having a width which is slightly smaller than the widthof a channel part, in applicable cases the diameter of a channel part.

The invention also relates to a heat-exchanger arrangement in which theexchange of heat is effected by advancing an energy-carrying medium in achannel system comprising mutually parallel and adjacent channel parts,such as hose parts, supported by essentially sheet or slab-like baseparts. The arrangement is mainly characterized by at least onepre-fabricated sheet of heat-insulating material, such as so-calledsolar plastic material, for supporting channel parts, said sheetincluding channel-part locking grooves which extend in the intendedlength direction of the channel parts and which, in applicable cases,have a width which is preferably slightly smaller than the width of achannel part, and when applicable receives the diameter of the channelpart.

The invention will now be described in more detail with reference to theaccompanying drawings, in which

FIG. 1 illustrates schematically part of a first embodiment of a channelpart supporting sheet or slab, said sheet being seen from above;

FIG. 2 is a sectional view taken on the line A--A of FIG. 1;

FIG. 3 illustrates schematically part of a second embodiment of achannel-part supporting sheet, or slab said sheet being seen from above;

FIG. 4 is a sectional view taken on the line B--B in FIG. 3;

FIG. 5 is a schematic, vertical sectional view taken transversely to thelongitudinal direction of the channel parts and shows a first embodimentof a heat-exchanger arrangement where sheets and channel parts arecovered with a layer of moisture-retaining filler material;

FIG. 6 is a schematic, sectional view essentially similar to FIG. 1 andshowing a second embodiment of a heat-exchanger arrangement where anupper layer of discrete plates, for instance, concrete slabs, aredisposed;

FIG. 7 is a schematic sectional view essentially similar to FIG. 5 andshowing a third embodiment of a heat-exchanger arrangement whereconcrete has been cast over sheets and channel parts;

FIG. 8 is a schematic sectional view essentially similar to FIG. 5, of afourth embodiment of a heat-exchanger arrangement, where concrete hasbeen cast over sheets and channel parts and where buttress-likereinforcements and screeding abutments are provided;

FIG. 9a through FIG. 9h illustrate various vertical-sections of groovesformed in channel parts, certain of said grooves constituting lockinggrooves;

FIG. 10 illustrates schematically the formation of locking grooves withthe aid of studs which are shown in vertical section taken on the lineC--C in FIG. 11;

FIG. 11 illustrates the arrangement of FIG. 10;

FIG. 12 is a schematic, vertical sectional view taken transverselythrough the channel parts of a fifth heat-exchanger arrangement, where aconcrete surface covering has been cast on site;

FIG. 13 is a schematic, sectional view of a sixth heat-exchangerarrangement essentially similar to FIG. 12, where a concrete surfacecovering has been cast on site;

FIG. 14 is a schematic, perspective view of a straight-edge arrangementoperative to produce a patterned covering;

FIG. 15 illustrates schematically and from above a seventhheat-exchanger arrangement where an inner floor is placed on sheetsincorporating channel parts, the upper layer of the floor being removedin FIG. 15, however; and

FIG. 16 is a sectional view of FIG. 15, with the upper layer shown.

FIG. 1 illustrates a channel system 1 comprising a plurality of channelparts, such as hose parts. The channel parts are intended to convey anenergy-carrying medium (not shown) and are supported on a pre-fabricatedsheet or slab 2 of heat-insulating material, such as so-called cellularplastic material, which forms a channel-part supporting base member.

The illustrated arrangement also includes short channel-part lockinggrooves 3 incorporated in the sheet or slab 2. The width of respectivelocking grooves will preferably be slightly smaller than the width of achannel part, when appropriate the diameter of said channel part, asillustrated in FIG. 1. The supporting sheet or slab will preferably bemade from a material which will as to provide a degree of resilience tothe walls of the locking grooves, such that said grooves will openagainst a spring force when a channel part 1 is pressed thereinto,therewith holding the channel part to a certain extent.

Locking grooves of mutually different configurations are describedhereinafter with reference to FIGS. 9a-9h.

According to one preferred embodiment, the locking grooves are formed inchannel-part support grooves 4. The grooves 4 are preferablycomparatively wide. In the FIG. 1 embodiment, the grooves widenessentially from a bottom part 5, so that the upwardly facing mouth 6 ofeach groove will have a width in the order of twice the largestcross-dimension of a channel part, in this case the diameter of saidchannel part.

The embodiment illustrated in FIG. 1 thus comprises a sheet or slab 2 inwhich a plurality of essentially parallel supporting grooves 4 extendside-by-side between mutually opposing end walls 7, of which one isshown in FIG. 1, and at least one locking groove 3 is provided in eachsupporting groove 4 between said end walls. In the illustratedembodiment, the end walls 7 are configured as locking grooves inconnection with said supporting grooves 4. Also shown are lockinggrooves 3 included in a transverse wall 8 in said supporting grooves,said wall 8 blocking said grooves, with the exception of the lockinggroove.

Similar to the FIG. 1 embodiment, the cross-sectional shape of thelocking grooves conforms to the cross-sectional shape of the channelparts, therewith enabling water to be retained for a longer period oftime between such locking grooves when a channel part is inserted intothe locking grooves 3.

FIGS. 3 and 4 illustrate an embodiment in which the channel parts 1 liein a common supporting groove 4 between rim parts 4' which extendsubstantially parallel with the channel parts.

In many cases of several applications, such as in the case ofartificially frozen ice rinks for instance, a moisture-retaining fillermaterial 9, such as sand, is appropriately placed around the channelparts in said grooves 4, as illustrated in FIGS. 5 and 6. This materialis intended to be substantially saturated with water, with the intentionof achieving good heat transfer between the channel parts and thesurrounding medium or media. In such applications, the sheets or slabsare also preferably covered with a layer of moisture-retaining fillermaterial 9. Grooves 4, such as the grooves 4 illustrated in

FIG. 9a-FIG. 9d, may also conceivably form locking grooves, Channelparts 1 are being intended to be held firmly, to some extent, in thesegrooves with the aid of preferably of fine-grain filler material. Inthis case, the locking grooves, at least at certain parts of the groovecross-section, will therefore be noticeably wider than the channelparts.

The embodiment illustrated in FIG. 6 includes discrete concrete slabs 9'which are laid on filler material 9 to form an upper covering.

The transportation of heat and water in the FIG. 5 and 6 embodiment willbe described hereinafter.

In the FIGS. 7 and 8 embodiments, concrete 10 is cast over the sheets orslabs 2 which support the channel parts 1. In the FIG. 7 embodiment, arelatively thick concrete layer has been cast, in order to achieve therequisite mechanical strength.

In order to achieve the requisite mechanical strength and anchoragesbetween slabs 2 and concrete 10, the slabs can be provided with recesses2' and/or promontories 2" which are respectively filled with or embeddedin concrete, said recesses and/or promontories being disposed in a givenpattern. This will enable a somewhat thinner concrete layer to be used.In the case of the FIG. 8 embodiment, concrete reinforcing buttresses 11are used to form a pattern of thickenings 11 of concrete layer in theslabs or sheets, a substantial part of the thickenings being disposed inslab parts 12 between said grooves 4. FIG. 8 also shows that the slabsor sheets may include screeding abutment elements or straight-edges 13which form an up-standing framework and which are intended to formabutments for coaction with strikers during a concrete casting operationand also to divide the concrete surface into smaller sections. Thestraight-edges 13 also form dilation joints which function to take-upmovement in the concrete surface. The straight-edges or plates 13 canalso be arranged adjacent edge parts of the slabs or sheets and morecentrally of said edge parts.

FIG. 9 illustrates various groove embodiments and shows the embodimentsFIGS. 9a-9d as examples of configurations in which a low thermallyactive mass is disposed between the pipes, while the embodiment FIGS.9e-9g are examples of a channel-part locking where the groove has beenexpanded when pressing a channel part thereinto, in order to achievelong term locking of the channel part. The locking surfaces of thelocking groove need only reach to about 60% of the diameter of thechannel-part concerned, as in FIG. 9g. An example of densely packedchannel-parts locked in respective locking grooves is shown in theillustration FIG. 9h.

FIGS. 10 and 11 illustrate a slab or sheet embodiment in which studs 14are operative to clamp channel parts firmly therebetween. The size,diameter, of the studs, can, of course, be varied and may well begreater than that illustrated in FIGS. 10 and 11, seen in relation tothe diameter of the channel-parts. The studs may conceivably bedistributed in a pattern which will create a "universal slab", in whichchannel parts may extend in any desired direction and also turn or swingbetween the studs.

FIGS. 12 and 13 illustrate two different embodiments of on-site castouter coverings, where concrete is cast on sheets or slabs 2 havingchannel parts 1 disposed therein. The FIG. 12 embodiment has awave-shape transversely to the direction in which the channel partsextend. The FIG. 13 has a stepped configuration, as shown highlyschematically in FIG. 14, formed with the aid of upstandingrim-elements/striker-straight edges 15 in the extension direction of thechannel parts.

FIGS. 15 and 16 illustrate arrangements using sheets or slabs in whichthe channel parts are accommodated in preferably essentially parabolicgrooves 14, wherewith the ridges 4' between the grooves form supportsfor a floor surface 16 in the form of sheets, slabs 16 or the like andwhich incorporate locking grooves 3. The channel parts, the hoses, arepreferably black, warm and dull, and radiate heat radially, said heatbeing reflected by preferably white and smooth, parabolic surfaces ofthe sheet or slab material, the cellular plastic material. In this case,heat transfer is effected by radiation and convection. Ventilating slotsare preferably provided on the undersurface of the sheets or slabs.

The method and the manner of operation of the arrangement according tothe invention will be understood essentially from the aforegoing.

Because the channel system 1 is disposed on heat-insulating sheets orslabs 2, the mutual effect between the channel system and the substrateor base support, i.e. the ground or the like, will be greatly reduced.The left-hand part of the FIG. 5 illustration shows the transport ofheat from the surface of the arrangement, the ice, in full-line arrowsand also shows to a limited extent the transportation of heat from theunderlying ground through the sheet or slab 2. Shown to the right inFIG. 5 is, among other things, the drainage of water in joints locatedbetween respective sheets or slabs 2. The filler material can thus besaturated with moisture through grooves 4. Surplus water drains-offthrough the joints between respective sheets or slabs. This moisturesaturation provides highly efficient heat transfer between the channelparts and the surrounding medium or media.

As illustrated in FIGS. 7 and 8, concrete can be cast directly onto thesheets or slabs containing channel-parts, wherewith a pattern ofreinforcements 11 can be employed to decrease the average thickness ofthe concrete layer while maintaining mechanical strength, as illustratedin FIG. 1, and therewith also reducing the amount of thermally activemass. The striker-abutment elements 13 form spacer elements, both whenstriking-off surplus concrete and when dividing the concrete surfaceinto sections. The striker-abutment elements can be left in the concretesurface, scraped out slightly and replaced with other material, such asconcrete.

Placing of the channel parts 1 and the durability or permanence of thechannel system with regard to its configuration are facilitated by thelocking grooves 3. Thus, the channel parts, the hoses, can be readilytramped into the locking grooves during successive placing of saidchannel parts, therewith fixating the hose or channel parts against bothaxial and radial movement.

When the channel parts are pressed into respective locking grooves, saidlocking grooves preferably having an essentially U-shaped cross-section,the grooves will first widen and then exert a clamping action on saidchannel parts, so as to prevent movement of said parts and, inter alia,upward deflection thereof. The frictional forces exerted by the lockinggrooves, even short locking grooves, are sufficiently large to impedechanges in length of the channel parts during the fitting of said partsand even when the rink, pitch or like area is used in the summer monthsas, for instance, a football pitch.

Because the channel-parts fit sealingly into the locking grooves, thereis formed a water-retaining damming construction which results inmoisture saturation of the filler material used.

The channel system is constructed by placing sheets or slabs 2sequentially in the intended direction of extension of the channelparts, several rows of sheets or slabs being placed adjacent oneanother. The channel-parts, the hose-parts, are laid in endless loops ofreciprocating lengths having an 180°-swing between each pair ofsequential lengths extending in the flow direction of theenergy-carrying medium, wherewith the channel lengths of one suchchannel pair need not necessarily lie adjacent to one another, but thatthe channel parts may be laid so that, upon completion, one or morechannel lengths will be located between the two lengths of one suchpair. In this case, the radius of curvature in each 180°-swing can bemade larger than when the channel length of each channel pair shall lieimmediately adjacent one another.

It will be seen from the aforegoing that the inventive method andarrangement afford important advantages of the kind mentioned in theintroduction.

The invention has been described in the aforegoing with reference toexemplifying embodiments thereof. It will be understood, however, thatother embodiments and minor modifications to the illustrated embodimentsare conceivable within the scope of the inventive concept.

The sheets or slabs 2 will preferably be made of expanded styrene,propylene or ethylene plastic, although said sheets or slabs may also becast directly in moulds from foamed polyurethane or polystyrene.

Working from smooth sheets or slabs is also possible principle. The slabmaterial will preferably be relatively hard.

Due, among other things, to the sealing contact achieved between lockinggroove and channel parts, there is obtained a damming effect whichenables the filler material used to be saturated with moisture,resulting in good heat transfer and effective use of the refrigerantconcerned. This damming effect can be amplified by providing a raisedrim 4' around the outer edges of the sheet or slab, as a complement tothe sealing locking grooves etc., as illustrated in FIGS. 3 and 4.

It is preferred in many instances to form in the outer edges of thesheets or slabs 2 draining slots 17 which lead to the underlyingsubstrate or foundation, as shown in FIGS. 1, 3 and 4. Surplus water inthe gravel layer, or rain water, is therewith enabled to drainhorizontally through the gravel layer up to the drainage slots, andthere pass vertically through the gravel-filled slots down onto adrainage foundation. Naturally, the drainage slots 17 can be formed inseveral different ways and may have different sizes and differentposition patterns.

According to one preferred embodiment, a number of the aforedescribedconstructional elements, i.e. grooves 4, locking grooves 3, recesseswhich form buttress-like reinforcements 11 and drainage columns in outeredges, are formed integrally with the sheets or slabs.

Consequently, the invention is not restricted to the aforedescribed andillustrated exemplifying embodiments thereof, since modifications andchanges can be made within the scope of the accompanying claims.

I claim:
 1. A heat-exchange method for making artificially frozen iceareas in the form of ice-rinks, comprising: advancing an energy-carryingmedium through a channel system comprising hose-like channel parts;providing a base for the frozen ice area comprising at least onepre-fabricated flat slab of heat insulating material with a pair ofopposed end edges and with a plurality of parallel, spaced-apartsupporting grooves for the channel parts; said supporting grooves beingmade integral with the slab and having open tops and concave, curvaturecross sections, extending along the upper surface of the flat slabbetween the opposed slab end edges; providing, on the upper surface ofthe slab, within the supporting grooves, a plurality of locking grooveunits with locking grooves, structurally integral with the slab andspaced-apart along each supporting groove, the locking grooves of thelocking groove units being made with a partially circular cross-section,the upper portion being open and the lower portion being coextensivewith the lower most curved surface of the associated supporting groove;extending, disposing, supporting and holding the channel parts inlengths disposed in mutually parallel side-by-side relationship on saidat least one pre-fabricated slab of heat-insulating material; and, whendisposing the channel parts on the slab, inserting the lengths ofchannel parts into the supporting grooves and into the spaced-apartlocking grooves associated with the supporting groove formed in saidslab, each of said locking groove units having a short length in thedirection of extension of the channel part when placed in the lockinggroove so the locking grooves engage only a minor part of the totallength of the channel parts; the open upper part of said supportinggrooves being wider than the cross-sectional dimension of the hose-likechannel part; making each locking groove unit (3) resilient so it iswidened against a resilient spring-like biasing force when the channelpart (1) is inserted and forced into the locking groove, to therebyfirmly hold the channel part in the locking groove, axially as well asradially, and forming a water-retaining damming construction between thechannel part and the bottom of the associated supporting groove, tothereby provide a sealed fit of the channel part (1) along theassociated locking groove units and the associated supporting groove;placing moisture-retaining filler material (9) selected from materialincluding sand and gravel, around the channel parts and covering theslab; and substantially saturating said filler material with water.
 2. Amethod according to claim 1, further including the step of castingconcrete (10) over the slab having channel parts incorporated therein.3. A method according to claim 2, further including the steps ofmutually anchoring the slab (2) and the concrete (10) with the aid ofrecesses (2') and promontories (2") formed in said slab, and providingthat the recesses and promontories are filled with and cast in saidconcrete.
 4. A method according to claim 3, including the step of usingthe promontories (2") as striker-abutment means (13) during a concretecasting operation.
 5. A heat exchange method as defined in claim 1,wherein said slab material is a cellular plastic material.
 6. Aheat-exchanger arrangement for creating artificially frozen ice areas,in the form of ice-rinks, in which an energy-carrying medium is forcedalong a channel system comprising: lengths of mutually adjacent parallelhose-like channel parts, and at least one pre-fabricated slab ofheat-insulating material with opposed end edges, having a plurality ofconcave curvature supporting grooves open along their upper side,extending between two opposed end edges of said slab, for supportingsaid lengths of channel parts, said slab including a plurality ofstructurally integral channel-part locking groove units including openupper side locking grooves with a concave inner curvature surface, theaxis of the locking grooves extending in the intended direction of thelengths of channel parts, the locking groove units being located in thesupporting grooves on said slab and spaced-apart along the supportinggrooves, the total of all locking grooves engaging only a minordimension of the total length of said channel parts, said locking grooveunits being short in their direction along the length of said supportinggrooves; said locking groove units being disposed in associatedsupporting grooves with the lower portion of the inner surface beingcoextensive the lower curved surface of the associated supportinggrooves; said supporting grooves at their open upper side being widerthan the cross-sectional dimension of a said hose-like channel part, andwherein the locking groove units (3) have a resilience enabling thelocking grooves to be widened against a spring-like bias force when achannel part (1) is inserted and forced into the locking groove unit,thereby firmly holding the inserted channel part tight against axiallydisplacement as well as against radial displacement, the lengths ofchannel parts thereby fitting sealingly in and coextensive with the baseof the associated locking grooves and the associated supporting grooveunits; each said locking groove contour conforming closely to thecross-sectional shape of the associated held channel part, so that awater-retaining damming construction between the channel part, thelocking groove units and the associated supporting groove is formed; amoisture-retaining filler material (9), selected from a group ofmaterial comprising sand and gravel, is placed around the channel partsand covers the entire slab and channel parts; and water is added to saidfiller material so that the filler material is substantially saturatedwith water.
 7. An arrangement according to claim 6, wherein the upwardlyfacing open side of each of said supporting grooves will have a width inthe order of twice the largest cross-sectional width of a channel part.8. An arrangement according to claim 6, wherein said slab (2) opposedspaced-apart edges have end parts (7), and also includes a plurality ofsaid mutually adjacent and essentially mutually parallel supportinggrooves (4) which extend between said two end parts (7) of the slab,wherein at least one of said locking groove units (3) is provided ineach of said supporting grooves (4) extending between said end parts. 9.An arrangement according to claim 8, wherein said end parts (7) areconfigured with integral locking grooves (3) in connection and having alower locking groove portion coextensive with said associated supportinggrooves (4).
 10. An arrangement according to claim 6, wherein atransverse wall is provided in said slab across said supporting grooves,and a locking groove unit (3) is incorporated in said transverse wall(8) coextensive with a said supporting groove (4), said transverse wallblocking said supporting groove with the exception of said lockinggroove.
 11. An arrangement according to claim 6 characterized in thatsaid sheet or slab containing said channel parts is covered with amoisture-retaining filler material (9).
 12. An arrangement according toclaim 11, characterized in that the slab includes recesses (2') andpromontories (2") which are respectively filled with concrete (10)achieving anchorage between said sheets and said concrete, said recessesand promontories respectively being disposed in a given pattern.
 13. Anarrangement according to claim 12, characterized in that concretebuttress-like reinforcements (11) are submerged as a pattern ofthickenings of the concrete layer in said slab, wherein a substantialpart of the buttress-like reinforcements (11) are disposed in slab parts(12) located between grooves (3, 4) in said sheet or slab.
 14. Anarrangement according to claim 11, characterized in that the concretesurface is divided into smaller sections.
 15. An arrangement accordingto claim 12, characterized in that promontories (2") to fromstriker-abutment means during the concrete casting operation.
 16. Anarrangement according to claim 12, characterized in that promontories(2") form a framework of striker abutments which divide the castconcrete layer into sections.
 17. An arrangement according to claim 6,wherein the outer edges of the slabs (2) are provided with drainageslots (17) operative to allow surplus water to drain-off towards thefoundation supporting said slabs.
 18. An arrangement according to claim6, wherein supporting grooves (4), locking grooves (3), recesses whichform buttress-like reinforcements (11) and drainage slots in outer edgesare formed integrally with the slabs (2).
 19. A heat exchangerarrangement as defined in claim 6, wherein said slab is made from acellular plastic material.